Considering object health of a multi-region object

ABSTRACT

A method for execution by one or more processing modules of one or more computing devices of a dispersed storage network (DSN) begins by identifying an unrecoverable encoded data slice of a data segment stored in a set of DSN storage units, where a region of a data object includes a plurality of data segments, and where the plurality of data segments includes the data segment. The method continues by determining whether the data segment is recoverable. The method continues, when recoverable, by salvaging the region by indicating that the region has corruption, updating a directory and replacing the data segment with filler data, and when not recoverable, by not salvaging the region by indicating that the region has been eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility patent application claims priority pursuant to35 U.S.C. §119(e) to U.S. Provisional Application No. 62/222,819,entitled “IDENTIFYING AN ENCODED DATA SLICE FOR REBUILDING,” filed Sep.24, 2015, which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility patent applicationfor all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of another embodiment of a dispersedstorage network (DSN) in accordance with the present invention;

FIG. 9A is a flowchart illustrating an example of managing datacorruption in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each of the managing unit 18 and the integrity processing unit20 may be separate computing devices, may be a common computing device,and/or may be integrated into one or more of the computing devices 12-16and/or into one or more of the storage units 36.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8. In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSTN memory 22for a user device, a group of devices, or for public access andestablishes per vault dispersed storage (DS) error encoding parametersfor a vault. The managing unit 18 facilitates storage of DS errorencoding parameters for each vault by updating registry information ofthe DSN 10, where the registry information may be stored in the DSNmemory 22, a computing device 12-16, the managing unit 18, and/or theintegrity processing unit 20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN memory 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSTN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate per-access billing information. In another instance, the DSTNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generateper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSTN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (TO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. The dispersed storage error encodingparameters include an encoding function (e.g., information dispersalalgorithm, Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides the data(e.g., a file (e.g., text, video, audio, etc.), a data object, or otherdata arrangement) into a plurality of fixed sized data segments (e.g., 1through Y of a fixed size in range of Kilo-bytes to Tera-bytes or more).The number of data segments created is dependent of the size of the dataand the data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 60 is shown inFIG. 6. As shown, the slice name (SN) 60 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

In a DSN memory, object data may be organized in a hierarchy, such thatcontent of a large dispersed object may be broken into many sections,each of which is independently processed with error correction composedof multiple “segments”, each of these segments then may be the unit uponwhich the IDA (Information Dispersal Algorithm) is applied to producemultiple slices for each segment. Each set of slices derived from eachdata source (in this case data source=segment) may be at a differentlevel of “health”.

For each segment, information such as: “What other segments are relatedto this segment?”; “What other regions are associated with the regionthis segment was a part of?” and “What other objects are associated withthe object this region was a part of in the context of a multipartobject?” may influence any strategy to recover or salvage one or moreassociated potentially corrupted and/or unrecoverable encoded dataslices.

When the set of all other segments that are related to this unavailablesegment are determined, the rebuilder may choose to: A. Deprioritizerebuilding of those other segments B. Cease any rebuilding activityrelated to those other segments C. Initiate cleanup operations of thoseother segments D. Continue rebuilding other segments of the object butflag this object as partially corrupted E. Create new readable segmentsto replace the missing ones which are filled with some predeterminedpattern (e.g., all zeros). Since the larger an object is, the morelikely it becomes that some part of it will be lost; the rebuild modulemay also adopt a policy (in the event of B) of placing a higher priorityon rebuilding the segment when an unhealthy segment has a larger numberof related segments.

FIG. 9 is a schematic block diagram of another embodiment of a dispersedstorage network (DSN) 10 that includes a storage set 900, the network 24of FIG. 1, and the distributed storage and task (DST) integrityprocessing unit 20 of FIG. 1. Storage set 900 includes a set of storageunits 1−n. Each storage unit may be implemented utilizing the DSTexecution unit 36 of FIG. 1. The DSN functions to manage datacorruption.

In an example of operation of the managing of the data corruption, theDST integrity processing unit 20 identifies an unrecoverable encodeddata slice of a set of encoded data slices, where a data object isdivided into a plurality of regions, where each region includes one ormore associated data segments, where each data segment is dispersedstorage error encoded to produce a set of encoded data slices that arestored in the set of storage units, and where at least a decodethreshold number of encoded data slices of the set of encoded dataslices are required to recover the data segment. For example, as shown,the data is divided into three regions, where a first region (region 1)includes two data segments, a second region (region 2) includes threedata segments, and a third region (region 3) includes two data segments.

The identifying includes one or more of interpreting an error message,receiving a list, interpreting integrity information 902 (e.g., slicestatus, storage unit status, etc.), and indicating the unrecoverableencoded data slice when less than the decode threshold number of encodeddata slices are available to reproduce the data segment (e.g., allstorage units reporting, less than all of the storage units reporting).For example, the DST integrity processing unit 20 receives, via thenetwork 24, integrity information 902 from each storage unit of the setof storage units and interprets the integrity information 902 toidentify numerous unrecoverable encoded data slices of the second datasegment of the second region when the integrity information 902indicates that less than the decode threshold number of encoded dataslices of a set of encoded data slices associated with the second datasegment of the second region are available. As another example, the DSTintegrity processing unit 20 interprets the integrity information 902 toidentify a third pillar slice of a third segment of the second region asunrecoverable when a decode threshold number of the storage units aretemporarily unavailable to provide encoded data slices of the thirdsegment of the second region.

Having identified the unrecoverable encoded data slice, the DSTintegrity processing unit 20 determines whether a data segmentassociated with the unrecoverable encoded data slice is recoverable. Thedetermining includes indicating that the data segment is unrecoverablewhen detecting that less than a decode threshold number of recoverableencoded data slices will ever be available from a given data segment.For example, the DST integrity processing unit 20 indicates that thesecond data segment of the second region is unrecoverable when detectingthat a decode threshold number of recoverable encoded data slices willnever be available from the storage units for the second data segment ofthe second region. As another example, the DST integrity processing unit20 indicates that the third data segment of the second region may berecoverable (e.g., is not unrecoverable at this point) when detectingthat a decode threshold number of recoverable encoded data slices maybecome available as more storage units become available (e.g., afterbeing temporarily currently unavailable) to produce the recoverableencoded data slices.

Having identified the unrecoverable data segment, the DST integrityprocessing unit 20 determines whether to salvage a region that includesthe unrecoverable data segment. The determining may be based on one ormore of an association of data segments to the region, an association ofthe region to another region, a predetermination, a request, a regionpriority indicator, a region priority threshold level, a comparison ofthe region priority indicator to the region priority threshold level, aregion type indicator, and interpreting system registry information. Forexample, the DST integrity processing unit 20 determines to not salvagethe second region when a region priority indicator has less than aregion priority threshold level for salvaging. As another example, theDST integrity processing unit 20 determines to salvage the second regionwhen an association of the second region to the first region indicatesthat the second region shall be salvaged.

When salvaging the region, the DST integrity processing unit indicatesthat the region has corruption. The indicating includes at least one ofupdating a directory, including a corruption flag within at least oneencoded data slice of the set of encoded data slices, and replacing theunrecoverable data segment with filler data (e.g., random data, allzeros, all ones, or a predetermined pattern). When salvaging the region,for each other unrecoverable encoded data slice that is associated withat least one other data segment of the region, the DST integrityprocessing unit 20 sends a rebuilt encoded data slice as a replacementencoded data slice 904 to the storage set. The sending includesobtaining a decode threshold number of recoverable encoded data slicesof the set of encoded data slices to utilize and generating the rebuiltencoded data slice and issuing write slice requests to a correspondingstorage unit of the storage set. For example, the DST integrityprocessing unit 20 recovers a decode threshold number of recoverableencoded data slices of the third data segment of the second region,produces a rebuilt encoded data slice 3, and issues a replacement slicemessage to the storage unit 3, where the replacement slice messageincludes the rebuilt encoded data slice 3.

When salvaging the region, the DST integrity processing unit 20facilitates neutralizing the region. The facilitating includes one ormore of updating the directory to indicate that the region is not valid,creating filler data segments for substantially all data segments of theregion, delete slices of substantially all of the data segments of theregion, and eliminating any queued tasks related to rebuilding encodeddata slices associated any of the data segments of the region.

FIG. 9A is a flowchart illustrating an example of managing datacorruption. In particular, a method is presented for use in conjunctionwith one or more functions and features described in conjunction withFIGS. 1-2, 3-8, and also FIG. 9.

The method begins or continues at step 906 where a processing module(e.g., of a distributed storage and task (DST) client module of a DSTintegrity processing unit) identifies and unrecoverable encoded dataslice of a data segment stored in a set of storage units, where a regionof a data object includes a plurality of data segments, and where theplurality of data segments includes the data segment. The identifyingincludes at least one of interpreting received integrity information,receiving a list, and interpreting an error message.

The method continues at step 908 where the processing module determineswhether the data segment is recoverable. The determining includesindicating that the data segment is unrecoverable when less than adecode threshold number of recoverable encoded data slices will ever beavailable. When the data segment is unrecoverable, the method continuesat step 910 where the processing module determines whether to salvagethe region. The determining may be based on one or more of anassociation of data segments to the region, an association of the regionto another region, a predetermination, a request, a region priorityindicator, a region priority threshold level, a comparison of the regionpriority indicator to the region priority threshold level, a region typeindicator, and interpreting system registry information. The methodbranches to step 916 where the processing module indicates that theregion has been eliminated when the processing module determines not tosalvage the region. The method continues to step 912 where theprocessing module indicates that the region has corruption when theprocessing module determines to salvage the region.

When salvaging the region, the method continues at step 912 of theprocessing module indicates that the region has corruption. Theindicating includes at least one of updating a directory and replacingthe data segment with filler data. For each other unrecoverable encodeddata slice that is associated with at least one other data segment ofthe region, the method continues at step 914 where the processing modulesends a rebuilt encoded data slice to a corresponding storage unit ofthe set of storage units. The sending includes obtaining a decodethreshold number of recoverable encoded data slices of the set ofencoded data slices to utilize and generating the rebuilt encoded dataslice and issuing a write slice request to the corresponding storageunit of the set of storage units, where the write slice request includesthe rebuilt encoded data slice.

When not salvaging the region, the method continues at step 916 wherethe processing module indicates that the region has been eliminated. Theindicating includes one or more of updating the directory to indicatethat the region is not valid, creating filler segments, and deletingslices of all data segments of the region. For each other unrecoverableencoded data slice that is associated with at least one other datasegment of the region, the method continues at step 918 where theprocessing module de-prioritizes an associated rebuilding task. Thedeprioritizing includes eliminating or lowering of a priority of anyqueued tasks related to rebuilding unrecoverable encoded data slicesassociated with other data segments of the region.

The method described above in conjunction with the processing module canalternatively be performed by other modules of the dispersed storagenetwork or by other computing devices. In addition, at least one memorysection (e.g., a non-transitory computer readable storage medium) thatstores operational instructions can, when executed by one or moreprocessing modules of one or more computing devices of the dispersedstorage network (DSN), cause the one or more computing devices toperform any or all of the method steps described above.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for execution by one or more processingmodules of one or more computing devices of a dispersed storage network(DSN), the method comprises: identifying an unrecoverable encoded dataslice of a data segment stored in a set of DSN storage units, where aregion of a data object includes a plurality of data segments, and wherethe plurality of data segments includes the data segment; determiningwhether the data segment is recoverable; and when recoverable, salvagingthe region by indicating that the region has corruption, updating adirectory and replacing the data segment with filler data; and when notrecoverable, not salvaging the region by indicating that the region hasbeen eliminated.
 2. The method of claim 1, wherein the identifyingincludes at least one of: interpreting received integrity information,receiving a list, or interpreting an error message.
 3. The method ofclaim 1, wherein the determining includes indicating that the datasegment is unrecoverable when less than a decode threshold number ofrecoverable encoded data slices will ever be available.
 4. The method ofclaim 1, wherein the determining is based on one or more of: anassociation of data segments to the region, an association of the regionto another region, a predetermination, a request, a region priorityindicator, a region priority threshold level, a comparison of the regionpriority indicator to the region priority threshold level, a region typeindicator, or interpreting system registry information.
 5. The method ofclaim 1, wherein for each other unrecoverable encoded data slice that isassociated with at least one other data segment of the region, sending arebuilt encoded data slice to a corresponding storage unit of the set ofDSN storage units.
 6. The method of claim 5, wherein the sendingincludes: obtaining a decode threshold number of recoverable encodeddata slices of a set of encoded data slices to utilize; generating therebuilt encoded data slice; and issuing a write slice request to thecorresponding storage unit of the set of DSN storage units, where thewrite slice request includes the rebuilt encoded data slice.
 7. Themethod of claim 5, further comprising determining that a set of allother segments that are related to an unrecoverable segment areunavailable and initiating one or more of: deprioritizing rebuilding ofthese other segments; ceasing any rebuilding activity related to theseother segments; initiating cleanup operations of these other segments;continue rebuilding other segments of the data object but flag this dataobject as partially corrupted; or creating new readable segments toreplace data segment with filler data.
 8. A processing unit within adispersed storage network (DSN) comprises: an interface; a local memory;and a processing module operably coupled to the interface and the localmemory, wherein the processing module functions to: identify anunrecoverable encoded data slice of a data segment stored in a set ofDSN storage units, where a region of a data object includes a pluralityof data segments, and where the plurality of data segments includes thedata segment; determine whether the data segment is recoverable; andwhen recoverable, salvage the region by indicating that the region hascorruption, updating a directory and replacing the data segment withfiller data; and when not recoverable, not salvage the region byindicating that the region has been eliminated.
 9. The processing unitof claim 8, wherein the identifying of an unrecoverable encoded dataslice of a data segment stored in a set of DSN storage units includes atleast one of: interpreting received integrity information, receiving alist, or interpreting an error message.
 10. The processing unit of claim8, wherein the determining whether the data segment is recoverableincludes indicating that the data segment is unrecoverable when lessthan a decode threshold number of recoverable encoded data slices willever be available.
 11. The processing unit of claim 8, wherein thedetermining whether the data segment is recoverable is based on one ormore of: an association of data segments to the region, an associationof the region to another region, a predetermination, a request, a regionpriority indicator, a region priority threshold level, a comparison ofthe region priority indicator to the region priority threshold level, aregion type indicator, or interpreting system registry information. 12.The processing unit of claim 8, wherein for each other unrecoverableencoded data slice that is associated with at least one other datasegment of the region, sending a rebuilt encoded data slice to acorresponding storage unit of the set of DSN storage units.
 13. Theprocessing unit of claim 12, wherein the sending includes: obtaining adecode threshold number of recoverable encoded data slices of a set ofencoded data slices to utilize; generating the rebuilt encoded dataslice; and issuing a write slice request to the corresponding storageunit of the set of DSN storage units, where the write slice requestincludes the rebuilt encoded data slice.
 14. The processing unit ofclaim 12, further comprising determining that a set of all othersegments that are related to an unrecoverable segment are unavailableand initiating one or more of: deprioritizing rebuilding of these othersegments; ceasing any rebuilding activity related to these othersegments; initiating cleanup operations of these other segments;continue rebuilding other segments of the data object but flag this dataobject as partially corrupted; or creating new readable segments toreplace data segment with filler data.
 15. A non-transitory computerreadable storage medium comprises: at least one memory section thatstores operational instructions that, when executed by one or moreprocessing modules of one or more computing devices of a dispersedstorage network (DSN), causes the one or more computing devices to:identify an unrecoverable encoded data slice of a data segment stored ina set of DSN storage units, where a region of a data object includes aplurality of data segments, and where the plurality of data segmentsincludes the data segment; determine whether the data segment isrecoverable; and when recoverable, salvage the region by indicating thatthe region has corruption, updating a directory and replacing the datasegment with filler data; and when not recoverable, not salvage theregion by indicating that the region has been eliminated.
 16. Thenon-transitory computer readable storage medium of claim 15, wherein theidentifying an unrecoverable encoded data slice of a data segment storedin a set of DSN storage units includes at least one of: interpretingreceived integrity information, receiving a list, or interpreting anerror message.
 17. The non-transitory computer readable storage mediumof claim 15, wherein the determining whether the data segment isrecoverable includes indicating that the data segment is unrecoverablewhen less than a decode threshold number of recoverable encoded dataslices will ever be available.
 18. The non-transitory computer readablestorage medium of claim 15, wherein the determining whether the datasegment is recoverable is based on one or more of: an association ofdata segments to the region, an association of the region to anotherregion, a predetermination, a request, a region priority indicator, aregion priority threshold level, a comparison of the region priorityindicator to the region priority threshold level, a region typeindicator, or interpreting system registry information.
 19. Thenon-transitory computer readable storage medium of claim 15, wherein foreach other unrecoverable encoded data slice that is associated with atleast one other data segment of the region, sending a rebuilt encodeddata slice to a corresponding storage unit of the set of DSN storageunits.
 20. The non-transitory computer readable storage medium of claim19, wherein the sending includes: obtaining a decode threshold number ofrecoverable encoded data slices of a set of encoded data slices toutilize; generating the rebuilt encoded data slice; and issuing a writeslice request to the corresponding storage unit of the set of DSNstorage units, where the write slice request includes the rebuiltencoded data slice.